I have always feared public presentations so I have given this a lot of thought.
I my life there are two types of presentations I have to give:
1) when I know what I’m talking about (like in school) and
2) when I have no or only a slight grasp of what I’m talking about.
When I don’t know what I’m talking about I have to memorise everything and nothing to learn anyone as far as presentations skills go.
When I do know what I’m talking about I never write a full script but only bullet point (for myself). A strict script makes me stumble if I get off track, and if I know the subject well I can often find a better place to continue that a script would allow me. The bullet point in my head keeps me on track, but don’t tie me down.
Are you using slides? When I use slides I try to avoid text as much as possible and rather present an inspirational picture or a diagram or something that is easy to take in but does not demand concentration from the listener. If I have to use text I use large font and key words. With to much text, the audience (even if it’s just one or two) will focus on reading and miss what you are saying, making everything more troublesome and disorganised. An inspirational picture or illustration can almost always be found – even if it’s, say, a presentation of a term sheet or a financial calculation.
For making my voice louder I do this: I steel myself, take a deep breath and say the first sentence in a loud voice and thus try to commit myself and my brain to speaking this way. It’s hard but once I get going it often works out better.
If your brain freezes (like mine do from time to, time) see that you have a glass or bottle of water to, sloooowly take a sip from as you regroup you brain cells.
Also, on TED there are numerous great presentations, ranked according to what makes them special, to steal ideas from.
Good luck!